1. Field of the Invention
The present invention relates to a color image forming apparatus, and more particularly to a method and apparatus for adjusting colors of an image read from a color original.
2. Related Art Description
In the fields of color printing and color copy, for example, a color of an image on a color original is separated into three primary colors by color filters of red (R), green (G) and blue (B), to obtain color signals of red, green and blue, respectively. Color signals of yellow (Y), magenta (M), and cyan (C), and if required, black (K) are formed from those color signals. In accordance with those formed signals, color materials such as color ink and color toner are outputted on a recording paper by a color hard copy machine, such as a color laser zerography, a color thermal printer, and a color ink jet printer.
Such a color image forming apparatus is capable of correcting colors by increasing or decreasing specific color signals of those color signals resulting from the color separation process.
The color correction process comes in the following two processes:
(1) masking for making a basic color correction for removing irregular absorption of ink or toner color, and
(2) masking for adjusting specific colors for correcting an abnormal color on an original image or for adjusting specific colors so as to satisfy user's tastes.
The masking (1) is used to cope with the difference of the spectral and reflecting characteristics of the color materials, such as color ink or color toner from the ideal characteristics. The masking (2) above can corrects a specific color on an original image whose saturation is lower than its normal saturation into a color of a normal saturation, by intensifying a color signal corresponding to that color. To change a specific color on the original to another color, a color signal corresponding to the specific color is weakened while a color signal corresponding to the desired color is intensified.
When the color adjustment is applied to the respective separated colors, yellow, magenta, cyan, and black, the number of the color adjustments is increased. Further, a high skill is required for a satisfactory color adjustment. In the printing field, for example, there is used a color separation scanner which separates a color on a color original and electronically forms three separated color plates. In the color separation scanner which is capable of adjusting yellow, magenta, cyan and black for six chroma of yellow, magenta, cyan, red, green, and blue, the number of color adjustments is 24. In the case of the scanner capable of adjusting light red and brown in addition to the above colors, the number of the color adjustments is further increased and is 32. Accordingly, the color adjustments becomes more difficult.
These color adjustments are extremely intricate, and requires professional skills.